Arrests were made in Portales, New Mexico, for alien smuggling but none are suspects in the investigation, Buie said.

Martinez died on Nov. 19, 2017, after he and his partner Stephen Garland, were found in a culvert area near Interstate 10, about 12 miles east of Van Horn, according to Buie.

Both agents were found with head and other physical injuries. They were hospitalized in El Paso, where Martinez died. Garland was released from the hospital a few days later. A U.S. official with knowledge of the investigation said he doesn’t remember what happened.

Buie said evidence showed that a Border Patrol dispatcher spoke with Garland the day of the incident. Garland was disoriented and unsure of his and Martinez’s location but said something to the effect of “we ran into a culvert,” "I ran into a culvert,” or “I think I ran into a culvert.” The dispatcher wrote Garland’s statement down and told him to go to his Border Patrol vehicle and turn on his emergency lights so first responders could locate him.

The autopsy report for Martinez revealed he died of blunt injuries to the head. Martinez suffered blunt injuries to his eyes, lacerations on his scalp, and fractures to his shoulder, ribs and clavicle, according to the autopsy report. How he sustained those injuries is still unknown.

The manner of his death is listed as “undetermined.”

Chris Cabrera, spokesman for the Border Patrol Union, issued a statement Wednesday, following the finding by the FBI. In it, he said the union's view hasn't changed.

"Our view is he was attacked," Cabrera said. After reading the autopsy report, Cabrera said he does not believe the agents were hit by a vehicle or fell in a culvert.

In the statement, FBI authorities said investigators conducted more than 650 interviews and involved 37 field offices, but have not found evidence of an attack.

“I know the danger out there. I have faith in the FBI. I know they will get to the bottom of this, " Cabrera said.

The FBI said they are continuing to investigate the incident and is asking anyone with information to contact the agency at 915-832-5000.

A reward of up to $70,000 by the FBI and state is being offered for tips leading to an arrest.

Speculation has run rampant with several politicians calling it an attack. President Donald Trump used the incident to renew his call for a border wall between the U.S. and Mexico.